Amyloses complexes

Enzyme—Heat—Enzyme Process. The enzyme—heat—enzyme (EHE) process was the first industrial enzymatic Hquefaction procedure developed and utilizes a B. subtilis, also referred to as B. amjloliquefaciens, a-amylase for hydrolysis. The enzyme can be used at temperatures up to about 90°C before a significant loss in activity occurs. After an initial hydrolysis step a high temperature heat treatment step is needed to solubilize residual starch present as a fatty acid/amylose complex. The heat treatment inactivates the a-amylase, thus a second addition of enzyme is required to complete the reaction. 

Note The reagent can be employed on silica gel and cellulose layers. Starch can also be employed in place of amylose [2]. The blue coloration of the amylose complex turns brown after a short time. 

Polycrystalline and well-oriented specimens of pure amylose have been trapped both in the A- and B-forms of starch, and their diffraction patterns84-85 are suitable for detailed structure analysis. Further, amylose can be regenerated in the presence of solvents or complexed with such molecules as alcohols, fatty acids, and iodine the molecular structures and crystalline arrangements in these materials are classified under V-amylose. When amylose complexes with alkali or such salts as KBr, the resulting structures86 are surprisingly far from those of V-amyloses. 

KOH-amylose complex, 346-347 A-Amylose, 340-342, 407-408 B-Amylose, 342-344, 409 V-Amylose, 345-346, 410 Analytical chemistry, 18 Anhydrides... 

FIGURE 6.16 AFM images of glucoamylase-amylose complexes and binding models. 

The physical form of the component is extremely important for ease of esterification for amylose, the order of reactivity is amylose complex > freeze-dried or freshly precipitated amylose > alcohol-precipitated, ether-dried amylose, whereas freeze-dried amylopectin is more reactive than... 

The results of these measurements, shown in Table VII, are obviously at variance. Some of the differences may be attributable to the different experimental conditions employed. Foster and Paschall178 have suggested that this change in Xmax is related to the state of aggregation of the amylose complex (from studies of the variation of Xmax with temperature), and have... 

Amylose complexes (wet precipitates) were prepared with fluoro-benzene, 1,1,2,2-tetrachloroethane, 1,1,2,2-tetrabromoethane, bromo-form, and ferf-butyl alcohol. The conformation and packing of the amylose chains complexed with halogen-substituted hydrocarbons are the same as found in the complex with tert-butyl alcohol, namely,... 

Partial hydrolysis with alpha amylase (EC 3.2.1.1), followed by gel chromatography, has been used to study aspects of the physical structures of the amylose complexes formed with such organic compounds as 1-butanol, and of retrograded amylose. Differences were detected.387b... 

The unit cell dimensions of all crystalline amyloses that have been determined in some detail, are listed in Table I. Also included are some intermediate forms between the va and Vjj amyloses (Ji.) and some V-amylose complexes with n-butanol, which, although not yet completely determined, have been added to illustrate the range of variability in unit cell dimensions. In the case of the Va-BuOH complex, a doubling of one unit cell axis was detected after a careful study of electron diffraction diagrams of single crystals ClO). A consequence of the doubling is that the unit cell now contains four chains, instead of the two normally found in amylose structures. Cln a strict sense, the A- and B-amyloses should also be considered as four-chain unit cells, but their double-helical structure still results in only two helices per cell) (13,1 ). 

A series of alkali-amylose complexes can be obtained during the solid-state deacetylation of amylose triacetate, as first described by Senti and Witnauer (32). The unit cells of the individual members of the series of LiOH-, K0H-, NH3OH-, CsOH and guanidinium hydroxide-adducts of amylose appeared to fit an iso-morphous series based on the space group P212 2i> and a tentative crystal structure was proposed (32). The detailed structure of the KOH-amylose complex has now been determined (ll) and the overall structure is similar to that proposed earlier. It is, therefore, likely that all members of the series are isomorphous. 

C-CP-MAS NMR produces a broad resonance with a chemical shift of 31.2 ppm,129 a characteristic of mid-chain methylene carbons of fatty acids in the V-amylose complex. The results showed that up to 43% of amylose in non-waxy rice starch, 33% in oat starch, and 22% in normal maize and wheat starch granules are complexed with lipids at a single helical conformation, and the remaining amylose is free of lipids and is in a random coil conformation.212 Up to 60% of apparent amylose in waxy barley starch is complexed with lipids.212... 

Krog, N. 1971. Amylose complexing effect of food grade emulsifiers. Starch 23, 206-210. 

Inclusion complexes of amylose are rather well defined, and a consistent theory of such complexes is available that explains amylose complexes with iodine, fatty acids, alcohols, and other guest molecules.4,5 This subject is surveyed in this article because of the growing interest and importance of such complexes in pharmacology and in the food industry. It is probable that starch in its biological sources (tubers, granules) exists in the form of native complexes with proteins, lipids, mineral salts, and water. 

Studies carried out in solution provide strong evidence that the helical amylose-iodine complex also exists in such circumstances.11014 1141 The structure of the iodine-amylose complex has also received theoretical treatment,142 and a three-dimensional free-electron model was developed for quantum mechanical calculations. Ultraviolet and visible spectra simulated in this manner reached close agreement with experiment observations. 

As with iodine, starch forms an inclusion complex with bromine vapor.205 Depending on the starch variety, different colors are developed by the complex. Maize and wheat produce an ochre color, rice produces a light-buff color, potato and sago develop a pale-yellow color, and cassava forms a cream color.69 Iodine cyanide (and bromine)-amylose complexes are brown-black and dark brown, respectively.206 The adsorption of chlorine and iodine proceeds according to the Freundlich isotherm. A discontinuity on the Freundlich isotherm plot is reported, which possibly results from the swelling of starch granules454... 

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